Pyro-recording paper



Patented Feb. 9, 1932 UNITED-STATES PATENT OFFICE RICHARD STUART BIGKNELL, OF RED BANK, AND RICHARD HOWLAND RANGER,

NEWARK, NEW JERSEY, ASSIGNORS TO RADIO CORPORATION OF AMERICA, A COR- PORATION OF DELAWARE PYRO-RECORDING PAPER No "Drawing.

and it is the primary object of this invention to provide a sensitized paper or support for this purpose. By pictures, Within the meaning of these specifications, are meant any dots or marks on a surface, wherein the dots or marks are of a different hue or intensity of color than the surface, and any marks used to make any sort of a visible record.

We are aware that paper and other materials have been used for recording telegraphic signals and that such have also been used for the record of pictures by chemical and photo-chemical reactions. Among these, for example, are preparations in which iodine has been liberated electrolytically. Such a method requires a substantial amount of water present and this makes the recording difficult and unsatisfactory, owing to the fact that the record is frequently not sharplv defined and hence not a faithful reproduction, and furthermore, the handling of wet papers for recording purposes is very difficult and inconvenient.

We are also aware of the use of sympathetic inks for recording purposes, the record being made visible while relatively dry by the aid of heat. By some of these methods the sensitizing material has been applied locally and the picture developed by a general application of heat or other means, the heat application being over the entire surface, to

both the sensitized and unsensitized portions of the surface.

The present invention consists of a sensitized paper or other support which is sensitized generally over the entire surface and Application filed August 30, 1928. Serial No. 803,108.

the picture developed by means of the local application of energy largely, if not exclusively, in the form of heat. The local application of heat results in producing dots or dashes as will be hereinafter indicated.

An object of our invention is to produce a chemical substance with which to coat or impregnate a paper, surface, or other supporting body which will render the same sensitive to heat.

Another object is to produce a paper which is practically dry and easily handled.

Another object is to produce a paper which may be used in daylight or sunlight if necessar nother object is to produce a paper capable of producing a picture directly without subsequent treatment to provide for permanence after the picture is made.

Another object is to produce a picture recording paper on which the recorded picture is substantially non-cracking, non-fading and sufficiently substantial to withstand the ordinary service and handling to which pictures are put.

Another object is to produce a recording paper, surface, or body which has more photographic qualities and is non-smudgmg.

Still another object is to produce a record ing paper, surface, or body which will be extremely rapid in recording and sensitive to the controlling medium.

- Other objects and purposes will be apparent from the following specification and claims.

The preferred method of recording by means ;of the heated air or gas jet, an electric spark or other similar means is explained in further detail by reference to patent application of R. H. Ranger, Serial No. 128,720

- filed August 12, 1926, and the transmitting and receiving 'of pictures by radio in its broad aspects has been described and claimed by applicant, R. H. Ranger, in certain of compounds, (V)

his copending applications of which the following are mentioned by way of example:

Serial number Title of invention Filing date 726,235 Duplex photo-modulator July 10, 1924 695,175 Method and means for reproducing and Feb. 16, 1924 transmitting pictures 750,514 Photo-amplifying system Nov. 18, 1924 3,911 Picture transmission Jan. 22, 1925 The present invention forms a continuation in part of our copending application Serial No. 158,406, filed Dec. 31, 1926, and relates to a paper or other suitable sensitized surface for recording the transmitted signals or pictures, and to the method and process of coating the said recording surface with a heat sensitive substance which, when exposed to heat' of any form, will produce the desired pigmentation.

For the purpose of classification, the various substances from which the coating solution is developed may be divided into a series of groups, such as, (I), organic compounds, (II), metal compounds, such as salts, (III), oxidizing agents, (IV),-sulphur adhesives or binders, and (VI), solvents.

To characterize each of these groupings by enumerating the various purposes thereof the organic compounds are principally substances which act to prevent crystallization with the application of heat and also substances which tend to vary the coloration of the picture, image, or marking impulse produced by the action of heat. I11 some cases the organic compound of the character to be hereinafter named may also act as binding or adhesive solutions without the need of a separate binder or adhesive, according to the grouping which is set forth and above named by Group V. The organic compounds consist principally in the phenol. nitro and amino derivatives of benzol and naphthaline and colloidal substances such as gelatin, agar, starch, casein, gum arabic, and certain forms of white or light colored sugars and the like. When the amino derivatives of benzol and naphthaline are used they are usually provided in the form of organic salts. For the .purpose of further identification of this group of elements which we have termed organic compounds we may state that they are compounds which are white or light colored and compounds which become colored by the application of heat thereto.

The second group of elements which we have identified as metal compounds are substances usually in the form of white or colored, simple or complex, salts which decompose or color with heat, with or without an oxidizing agent. These metal compounds or salts when applied to the paper produce a coating which is apparently colorless and the concentration of the salts upon the paper is so changed from the original appearance of the salts that when they are applied to the paper-or other recording surface in combination with one or more of the other groups of elements they present a substantially colorless appearance. These compounds may consist, for example, of compounds of nickel, copper, iron, cadmium, and the like, capable of reacting with an application of heat to form dark colored compounds, such as ox ides, hydroxides, sulphides, or halides, such as an iodide. These metal compounds may also be defined generically as metallic pyro recording materials.

The third group, above identified as the oxidizing agents, may consist, for example, of chlorates, oxides of the various metals which may be separate substances placed in solution with the other groups or may be found together with the various metals listed as metal salts or compounds in group II.

The sulphur compounds described as group IV may be, for example thiosulphates, sulphites, polythionates, or other inorganic or organic sulphur bearing compounds.

In the fifth group which we have termed the adhesive or binder group, the substances provided may be certain substances above identified as organic materials-and found in group I or other binders, and may consist, for example, of various colloids such as gelatin, agar, starch, casein, gum arabic, and the like, as well as various sugar solutions. In connection with this group of substances it should be borne in mind that while the substances herein named serve the purpose of binding the solution to the recording surface, they may also serve to govern the degree of coloration of the surface when exposed to heat. It will later be shown that the colloidal substance of this fifth group may be combined with any one of a plurality of solvents to be later described. whereby desired colloidal dispersion media may be produced.

Now referring to the solvent group which is provided for practical purposes and for the purpose of applying the solution to the paper or other suitable recording surface so that the liquids are in suspension and/or solution we may use and provide various substances such as water, various alcohols. acetone, ether, various organic esters, and other organic solvents, such as hydrocarbons or carbon bisulphide. Thus, where any of the substances herein named and/or included as solvents are in combination with any or all of the various organic binders or adhesives of the fifth group, an organic dispersion medium is produced, It will be noted that a colloidal dispersion medium is produced when any of the solvents of the aforcn'icntioned solvent group is utilized in combination with the various colloids of the above described fifth group.

nitrates, nitrites, and other The following table illustrates several of the various groupings of elements which we may provide.

Table of sensitizing solution compositions Organ- Organlc Non-oric and comgenie oomnoupounfls pounds organ- Grouping of elements pounds r A Solution number I-Organic compounds x x x x II-Metal compounds x x x x x III-Oxidizing agents... x x x x IV-Sulphur compounds x x x VAdhesive substances x x x x x x x VISo1vents x x x x x x x From the above table it may be seen that the elements may be grouped in two classifications. as A, where organic compounds of group I are used, and B, where no organic compounds of group I are used. However, it is to be understood, that any of the formulae, which are shown as 1, 2 and 3 in group A and as 4, 5 and 6 in group B may be combined with any formula in the other group so that the entire system as shown and illustrated by the few of the almost infinite number of examples is quite flexible and interchangeable and a composition, as formula 7, combining classes A and B has been found very suitable.

To illustrate, for example,various solutions which fall within the classification, as exhibited by the above table, we may illustrate a sensitizing composition such as shown by the following formula designated as formula 1 and classified under the organic compounds. This formula may include the following elements:

Anilin hydrochloride 5 parts Gelatin (or other binder of Group V) 1 part 2% aqueous alcohol 100 parts In this formula, above described, the anilin hydrochloride serves as an organic compound, the gelatin, or other binder of the class named in Group V, as an adhesive substance, and the aqueous alcohol as a solvent.

Coming within the same category as the formula above described as formula 1 is the second formula which we have identified as formula 2 in Group A which might consist, for example, of:

Phenol-phthalein part Salt 5 parts Gelatin 10 parts Water 100 parts where the phenol-phthalein serves as an organic compound and sens1t1zer.the salt serves as a metal compound, the gelatin, or other to be understood, that the proportions of the ingredients may be altered within wide limits for the purpose of obtaining similar and substantially as eflicient results.

While a composition of the character above specifically named and identified as formula 2 has been found to be useful and desirable it produces a coating on the paper which is not as sensitive as may be desired for recording pictures. To avoid this difficulty, therefore, in accordance with further developments of our invention we may employ substances for use as a coating or impregnating material which may react by the application of heat to form colored compounds which are decomposition products, polymers, oxidization products or products of other reactions which yield change in hue or intensity of color.

In accordance with this last named suggestion we might illustrate, for example, a sensitizing material in which a chemical action takes place and provide a composition consisting, for example, of

Anilin hydrochloride 9.8

where the anilin-hydrochloride acts or serves as an organic compound, and an oxidizing agent is provided by the potassium nitrate; a binding or adhesive substance is provided by the gelatin and a solvent is found in the form of water; as has been suggested by formula No. 3 under class A in the above table. As in the example previously set for formula No. 2, a solution of this character is also subject to wide variations as to the proportions of the various ingredients substances used or as to the substitution of equivalent substances above named in the various groupings without essentially changing or modifying the result produced, although it is possible that one solution might be slightly faster or slower than another, by which we mean that the paper reacts faster or slower to heat action. It is to be noted that the last named formula 3 is a development from the formula identified as 1, by means of the addition of an oxidizing agent thereto as an accelerator.

In accordance with further developments of our invention we have found that the employment of metallic salts which yield the desired pigmentation on application of heat which react under heat action to act to form sulphurccompounds of themetals.

We have noted that double salts are sometimes of lighter color than the simple salt of the metal and provide a coating which is white or nearly so, a distinct advantage for picture making purposes. Apparently double salts are sometimes more reactive or more easily decomposed than simple salts when heat is applied to them. Probably some complex salts react under influence of heat with initial exothermic reactions which result in the formation of colored compounds.

Generally, the metals in the form of light colored salts or compounds which decompose with heat with or without an oxidizing agent that may be used in the form of salts, and which have been found suitable are compounds of any of nickel, copper, manganese, lead, iron, cobalt, antimony, mercury, platinum, and the like which produce dark colored sulphides in combination with a sulphur bearing substance. Other metal compounds such as that of nickel, copper, iron, cadmium, and the like in combination with "e sulphur may produce dark oxides or hydroxides. Compounds of the precious metals, such as those of iridium, osmium, palladium, and the like may also be used.

In connection with the non-organic compounds we have developed several solutions which have been identified as solutions Nos. 4, 5 and 6. each containing certain of the groups of elements listed in the above table of sensitizing solution compositions. Now making reference to solution No. 4 specifical- 1y, we may provide a composition consisting of:

Nickel nitrate [Ni(NO -6H O] 10 parts Potassium chlorate KClO 5 parts Agar (orotherbinderof group V) 1 part Water 100 parts the above table where we may provide, if desired,

Cop er nitrate [Cu SNO -3H Oj 10 parts where the copper nitrate acts as a metal compound, the thiourea acts as a sulphur compound, the gum arabic as an adhesive substance, and the Water as a solvent for the solution so that it maybe applied to the paper or .other suitable surface used in the recording process. A further preferred form of sensitizing agent which may be coated upon the paper or other suitable surface has been illustrated by formula 6 in the above illustrated table setting forth several of the many formulae which might be used to coat or impregnate a paper or other suitable recording surface. Applying the formula illustrated as 6 above to various substances illustrated in the example We may suggest the following as suitable:

(II and III) Nickel nitrate In the last table of elements illustrating a specific example of the formuladesignated as 6 we have classified the respective elements and associated them with the various groups of elements merely by indicating in parenthesis before each element the number of the group with which it is associated for the purpose of identifying the elements in the formula and showing how it reacts with the other elements to produce a suitable paper.

In the last named formula, as in the previous examples, the ingredients suggested are subject to wide variations as to the proportions and suggested quantity of each or to the substitution of equivalents without producing any substantial changes in the coating solution. It has been found advisable under certain conditions to add organic materials to the above named composition and, in such case, these materials might be of the form of an anilin salt, organic salt, organic compound, or, in fact, any of the substances which would come within the disclosure of group I above identified as organic compounds, which will produce a wide color range in the paper after it has been exposed to heat in any preferred manner, to be hereinafter described.

After this coating or solution has been applied to the paper, the surface thereof is of a light color, in fact, nearly white, and quite flat, that is, not glossy and not microscopically distinctly crystalline. It can be seen that many other combinations of the various elements su gested in the last named formula are possi Is to produce identical results to those stated in the formula'and, for example, nickel nitrite and sodium nitrate might be substituted for nickel nitrate and sodium nitrite.

While it is not necessary, the use or addi tion of a colloidal substance, such as, gelatin} starch, dextrine, casein and other substances of the same classification, to the formula identified as 6 make a superior coating. When these substances are used, the salts upon drying upon the paper are more uniformly dispersed and the segregation of visible crystals is eliminated, or, at least, the crystals which form are so small as to be practically invisible and indeterminable.

By the preceding table we have illustrated several representative types of formulae which we might use for the purpose of coating a paper or other suitable support substance and have illustrated each of these several types of formulae by a specific example, and, by referring to the different materials which We have illustrated as falling within each of these separate classifications or groups, other solutions in accordance with the formulae, not specifically illustrated, will at once suggest themselves. By the table we have illustrated three possible solutions falling within the classification of organic compounds classed as A and three solutions classed as B or non-organic compounds but, it is to be understood, in accordance with the disclosure of this specification that any solution of either group A or group B may be mixed with any of the other solutions so as to form a more or less composite grouping, for example, if formula 1 were mixed with formula 6, as illustrated by formula 7, it will be noted, that each of the six groups of elements would be present, but, supposing formula 1 were mixed ,with formula 4:, a case would arise where all groups of elements with the exception of IV were present. Other similar combinations of these groupings will, at once, be apparent.

As above suggested we have indicated that it is possible to combine the various solutions indicated as Nos. 1, 2 and 3, of class A and solutions Nos. 4, 5 and 6 of class B which if Nos. 1 and 6 were combined, will produce a solution of the character indicated as solution 7. This solution has been found to produce exceptionally good results in working with radio and line signals for recording purposes and we have found that a solution consisting of:

(I) Anilin hydrochloride 5 parts (II and III) Nickel nitrate 5 parts (III) Sodium nitrite 3.6 parts (IV) Sodium thiosulphate -i 3 parts (V) Gelatin 1 part (VI) 2% aqueous alcohol 100 parts produces very satisfactory results. It is belived that from the foregoing'examples of the solutions that the group to which each of these separate elements are associated will at once be apparent, and, it will be seen, that formula 7 covers all of the groups of elements which are utilized in preparing the various solutions numbered as 1 through 6 in the table. It will be apparent further that various groups of elements may be omitted from the solutionnumbered as 7 and still produce satisfactory and efficient results in accordance with the manner suggested by the various solutions numbered as 1 through 6.

Making further reference to the illustrated formula numbered as 6', it is to be noted, that instead of using compounds of nickel, compounds of various other metals such as those of lead, copper, iron, and, in fact, any of the other metals above suggested which react to produce either dark oxides, sulphides, hydroxides, or halides or the like with the application of heat might be substituted, although, for the purpose of this patent specification, we have deemed it unnecessary to specifically illustrate the exact substitution of ingredients which might be applied with each possible formula, since the number of such formulae might run well into the thousands and still produce the same or equivalent results.

Again, in connection with the organic materials which have been added it is possible to materially change the proportion thereof without effecting the quality of the coating solution, since one organic material might produce, for example, a bluish tint to the finished picture, whereas another might produce a reddish tint to the finished picture, and if these two organic substances were used together in solution the result might be, for example, a finished picture of a brownish tint. These possibilities have been suggested for the reason that it is a well known fact that pictures having a reddish or brownish tint photograph better than pictures having bluish tints, and, it is for the purpose of obtaining a wide color range in the finished product that we have added these organic materials.

It will be noted from a consideration of all the solutions identified in the table as 1 through 7 that in each case a solvent is present. As have been previously stated, the solvent is used simply for the practical purposes and for ease in applying the solution to the paper or other suitable recording surface so that the various elements are in suspension and/or solution and when the paper to which the solution has been applied has been dried, of course, the solvent is no longer present in that it has been evaporated or absorbed to such an extent that the paper or other recording surface assumes a dried state,

Further research and study dlscloses the fact that the addition of a sulphur containing substance as identified by Group TV to the coating solution in many cases considerably augments the action of the heated air jet or other heat producing means for recording and produces a darker and more sharply defined result from the incoming signal pulses upon the paper or other supporting surface.

Using a coating for the recording paper, according to the last above described formula No. 7, for example, and a hot jet of a1r or other gas directed against the coated or 1mpregnated paper, temperatures of between 480 to 520 F. are suitable for full discoloration of the paper where the speed at which the jet of heated air or other gas travels across the paper is 1.5 inches per second. If a spark method of recording on the paper is utilized, the energy necessary between pointed electrodes spaced .02 inches apart to give full discoloration on the coated paper has been found to be between 20 and 25 watts.

It is important that the paper or support for the sensitizing material be suitable. It must not contain substances which in time will react with the sensitizing material. If paper is used it should be sufficiently tough and absorptive to make a durable sheet and uniform in quality. As the reaction of the sensitized paper tends to follow along the individual fibers of the paper rather than spreading to adjacent fibers, a relatively short fiber paper is desirable where sharpness of definition of the picture is desired. Smooth book papers and bond papers have been found adapted for this use, but other kinds of paper will serve.

A suitable means of recording pictures on this type of paper is set forth in detail in the Ranger application, Serial No. 128,720, above referred to, and preferably comprises the use of heat in any of the forms previously mentioned directed against the recording paper or surface. The preferable means of applying heat consists of a jet of hot air or other gaseous substances moved across the paper. Such a heating means, therefore, might comprise an air jet heated continuously and deflected through a small slit with reference to the py ro-recording paper so that the heated jet of air intermittently strikes the paper. The movement of the jet may be accomplished for example, by any preferred form of reciprocating mechanism such as is disclosed in the application heretofore mentioned in which the jet moves transversely across the paper and at the end of each stroke a stepping mechanism is used to advance the paper a slight amount, so that each reciprocation of the air jet will bring the said jet across a portion of the paper which has heretofore been unexposed to heat. The control of the jet may,

for example, be accomplished by an electromagnetic valve controlled from the received signals or by means of an ordinary telephone receiver the movement of the diaphragm of which serves to actuate a shutter associated with the air nozzle and placed in the stream of the heated air. Such a method as this is extremely rapid in recording and is Very sensitive.

Papers coated with solutions of the character described are capable of being used in daylight or sunlight if necessary and after being subjected to heat, in the manner above named, directly produce a picture which is permanent and needs no other treatment to present a finished appearance.

Having now described our invention We are entitled to all modifications thereof such as fall fairly within its spirit and scope as defined by the following claims, wherein:

W claim:

1. A liquid pyro recording composition containing a thermo-sensitive coloring material, an oxidizing agent, and an organic dispersion medium.

2. A liquid pyro recording composition containing a thermo-sensitive coloring material, an oxidizing agent, and a colloidal dis persion medium.

3. A liquid pyro recording composition containing a metallic pyro recording material, an oxidizing agent, and an organic dispersion medium.

4. A liquid pyro recording composition containing an organic pyro recording material, an oxidizing agent and an organic dispersion medium.

5. A liquid pyro recording composition including a thermo-sensitive coloring material, a sulphur bearing compound, and an organic dispersion medium.

6. A liquid pyro recording composition containing an organic thermo-sensitive coloring material, a sulphur compound adapted to accentuate the coloration with an application of heat to the composition, and an organic dispersion medium.

7. A liquid pyro recording composition containing a metallic thermo-scnsithe coloring material, a sulphur compound f or accentuating the coloration produced by said metallic compound upon the application of heat thereto, and a colloidal dispersion medium.

8. A liquid pyro recording composition containing a substantially colorless heat sensitive organic material, a metal compound, a sulphur compound, and an organic dispersion medium.

9. A liquid pyro recording composition containing a substantially colorless heat sensitive organic material, a metal compound, a sulphur compound, an oxidizing agent, and an organic dispersion medium.

10. A liquid pyro recording composition containing a color forming metal compound in combination with a thermo-sensitive sulphur bearing material, and a colloidal dispersion medium.

11. A pyro recording sheet comprising a fibrous body provided with a coating resulting from a mixture of a metallic thermosensitive coloring -material, an oxidizing agent, and an organic dispersion medium.

12. A pyro recording sheet comprising a w fibrous body provided with a coating resulting from a mixture of a thermo-sensitive coloring material, an oxidizing agent, and an organic dispersion medium.

13. A pyro recording sheet comprising a fibrous body provided with a coating containing a thermo-sensitive coloring material, an oxidizing agent, and a colloidal dispersion medium.

14. A pyro recording sheet comprising a fibrous body coated with a composition containing a gelatinous material, a metallic compound, and a sulphur bearing substance.

15. A pyro recording sheet comprising a fibrous body impregnated with a composition 25 containing gelatin together with a substantially colorless heat sensitive organic ma terial and an oxidizing agent.

16. A p ro recording sheet comprising a fibrous bo y provided with a coating containso ing a colloidal substance, a substantially colorless heat sensitive organic medium, and an oxidizing agent.

17. A. pyro recording sheet comprising a fibrous body having placed on the surface thereof a composition containing a metal salt together with an oxidizing agent and a sulphur bearing substance.

18. A pyro recording sheet comprising a fibrous body impregnated with a composition containing a colloid, a substantially colorless' heat sensitive organic material, a sulphur compound, and an oxidizing agent including a compound of nickel.

19. A pyro recording sheet comprising a fibrous body havin on the surface thereof a coating resulting irom a composition containing a substantially colorless heat sensitive organic material, a metal salt, and a colloidal dispersion medium. 20. A pyro recording sheet comprising a fibrous body impregnated with a composition containing a substantially colorless heat sensitive organic material, an oxidizing agent consisting of a metallic salt, and a sulphur bearing substance together with an organic dispersion medium.

21. For the pyro recordin of pictures, a record sheet impregnated wit a composition containing a colloidalsubstance, a substantially colorless heat sensitive organic material, a metal salt, and a sulphur bearing compound.

RICHARD STUART BICKNELL. RICHARD HOWLAND RANGER. 

